1. Field of the Invention
This invention is concerned with synthetic lubricating oil compositions for bus or truck turbine engines. More particularly, the invention relates to aliphatic esters formed by the reaction of a pentaerythritol and an organic acid having from 2 to 12 carbon atoms per molecule whose pour points have been depressed by blending therewith a synergistic mixture of at least one mineral oil and a methacrylate pour point depressant.
The above-mentioned esters are inexpensive and would adequately provide lubrication to turbine engines except for their high pour points. However, their pour points cannot be depressed if conventional depressants for mineral oils are used alone.
2. Description of the Prior Art
The prior art to which this invention relate is aware inter alia of the following U.S. Pat. Nos: 2,796,402; 2,796,403; 2,796,404; 3,412,028; 3,476,685; 3,321,402; and 3,779,919. The last mentioned discloses the esters of this invention but in combination with the amine salt of a substituted rhodanine which imparts thereto corrosion-inhibiting and load carrying properties under high thermal and oxidative stress.